1. Field of the Invention
This invention involves an apparatus and a method for inducing desired brain wave frequencies in a user by presenting periodic visual and audio signals, respectively, to the eyes and ears of the user.
2. Description of Related Art
It is well known that the human brain generates periodic electrical signals, commonly referred to as "brain waves." These brain waves range in frequency from about 1 Hz to about 36 Hz and, for ease of reference, are commonly divided into four or more groups. "Beta" waves (12 to 36 Hz) tend to dominate in the brain during normal waking activity; "Alpha" waves (8 to 12 Hz) have been discovered to occur most frequently when the person is relaxed; "Theta" waves (4 to 7 Hz) are most common during periods of sleep or deep meditation and also occur during periods of learning or memory recall; and "Delta" waves (1 to 4 Hz) appear most frequently during periods of the deepest sleep. These ranges of frequencies are approximate, but in general, the dominate brain wave frequency increases with increasing mental activity.
Experiments have indicated that when light is repeatedly flashed into the eyes of a subject within this frequency band, the brain waves of the subject tend to assume the frequency of the flashing. It has also been discovered that such "synchronization" of brain waves may lead to brain seizures in epileptics or in other people who have a history of brain seizures.
On the other hand, other experiments have demonstrated that pulsating light and sound can induce a synchronized pattern of brain waves. There is, furthermore, evidence to indicate that by inducing a subject's brain waves to come within the Alpha range, the subject at least will be able to relax better, and may even be able to learn more quickly and permanently. Many researchers also report that subject whose brain waves are caused to synchronize within the Alpha range or lower are better able to receive subliminal or audible audio messages.
Differential audio frequencies have also been shown to cause similar effects. For example, if the frequency of a tone played into one ear of a subject is 10 Hz higher than the frequency of a tone played into the subject's other ear, experimental evidence indicates that the subject's brain, acts in a way similar to a "heterodyne," tends to generate brain waves at a frequency approximately equal to the difference in frequency between the two tones, that is, in this case, 10 Hz. The same result arises when tones are alternately put to the left and right ears with a frequency equal to the desired synchronization frequency.
There are accordingly many devices now available that are designed to present flashing lights, alternating tones, or both, to the eyes and ears of a user. Some devices use "bio-feedback," in which the brain wave frequency of the user is sensed and used to control the frequency of the flashing lights or pulsating tones; the user herself thereby attempts to train herself to produce the desired frequency, which is reinforced by the flashing lights and pulsating tones. Many other devices, which do not measure the brain waves in an attempt to create a feedback loop, actively control the flashing or switching frequency. Examples of such devices are described in the following U.S. Patents.
______________________________________ U.S. Pat. No. Inventor(s) Issue Date ______________________________________ 5,064,410 Frenkel, et al. Nov. 12, 1991 5,036,858 Carter, et al. Aug. 6, 1991 4,955,389 Schneider Sept. 11, 1990 4,902,274 Gleeson, III Feb. 20, 1990 4,834,701 Masaki May 30, 1989 4,665,926 Leuner et al. May 19, 1987 4,632,126 Aguilar Dec. 30, 1986 4,456,347 Stahly June 26, 1984 4,396,259 Miller Aug. 2, 1983 4,335,710 Williamson June 22, 1982 4,315,502 Gorges Feb. 16, 1982 4,008,714 Silva et al. Feb. 22, 1977 3,882,850 Ballin et al. June 13, 1975 ______________________________________
All of these known devices create the synchronizing pulsed light and/or sound by actively generating an electrical pulse at the desired frequency. This electrical synchronization pulse activates a small set of lights in front of the user's eyes, and controls a tone generator whose signal is fed into earphones. In many of these known devices, the electrical pulses result from a timing program in the memory of a microprocessor or a computer. In some of these devices, the user herself selects the synchronization frequency. In other devices, one or more frequencies or programs of varying frequency are generated automatically, whereby the user, in some cases, can select which program she wishes to follow.
The foremost drawbacks of known devices for synchronizing brain waves are that these devices are complicated and expensive. They typically contain many mechanical and electrical components that require careful testing and calibration. Few are suitable for easy use by most individuals, and fewer still are within their budgets. Even the least expensive of these known devices sells at retail for prices on the order of hundreds of dollars.
In order to reduce complexity, at least one device (see the Gleeson patent) encodes control signals on magnetic tape. Such devices, however, typically require four or more audio channels simultaneously, so that they are not suitable for use in common 2-channel devices such as the portable stereo cassette tape players already owned by a large section of the population. Furthermore, the Gleeson device requires special conditioning circuitry separate from the tape player in order to drive the lights and speakers used; this increases design costs.
It is therefore an object of this invention to provide a device for inducing synchronized brain waves using both flashing lights and pulsating tones that is easy to use and that can be manufactured from inexpensive and compact components so as to make it much more affordable than existing devices.